2b5r

TEM1-β-Lactamase/ β-Lactamase Inhibitor Protein (BLIP)
(see also TEM1-beta-Lactamase/beta-lactamase Inhibitor Protein (BLIP))



The enzyme TEM1 β-lactamase (EC 3.5.2.6; TEM1) and its protein inhibitor, β-lactamase inhibitor protein (BLIP) form a complex. The TEM1-BLIP complex where BLIP residues of the bound structure are colored blue and of the unbound are in cyan. TEM1 residues from the bound complex are in red and from the unbound structure in yellow. BLIP and TEM1 residues are labeled blue and red. The <scene name='2b5r/Bound_unbound/4'>interface between BLIP and TEM1 was divided into six interface clusters (<scene name='2b5r/C1/2'>C1, <scene name='2b5r/C2/3'>C2 , <scene name='2b5r/C3/2'>C3 , <scene name='2b5r/C4/3'>C4 , <scene name='2b5r/C5/2'>C5 , <scene name='2b5r/C6/2'>C6 ). Superpositions of these clusters from TEM1–BLIP (complex-1jtg), TEM1 (unbound-1btl) and BLIP (unbound, Strynadka et al, 1994) structures are shown. <scene name='2b5r/C1mut/2'>Overlap of cluster C1 from TEM1-BLIP wt, mutant and unbound structures (<font color='red'>TEM1wt -<font color='blue'>BLIPwt complex, <font color='lime'>TEM1wt-BLIPD49A, <font color='black'>unbound TEM1 (yellow), and <font color='cyan'>unbound BLIP ). <font color='blue'>D49 in BLIP is located in the center of C1, surrounded by <font color='red'>4 TEM1 residues. The <font color='blue'>D49A mutation (i.e. removal of a side chain) does not cause structural change in the TEM1-BLIP complex.

To analyze the contribution of non-alanine mutations, E104Y and Y105N in the TEM1 protein were constructed. These residues are polar and have a similar size, hence no major structural changes are expected for these mutants. The complex structure of TEM1 E104Y-Y105N (TEM1YN) with BLIPwt was solved. The YN mutation caused only small reduction of binding energy (4.2 kJ/mol), which is slightly less then that obtained for the alanine substitutions of these residues. The <scene name='2b5r/Superpos/1'>superposition of <font color='magenta'>TEM1wt -<font color='black'>BLIPwt (yellow) complex (1jtg; <font color='magenta'>TEM1 colored in magenta; <font color='black'>BLIP in yellow ) with <font color='lime'>TEM1YN (colored in lime) - <font color='pink'>BLIPwt (pink) complex. Only a <scene name='2b5r/Superposition/12'>minor change <font color='orange'>(colored orange) in <scene name='2b5r/Superpos/2'>TEM1YN was observed. But, these small changes in TEM1 sequence lead to a major local <scene name='2b5r/Blip/3'>backbone rearrangement of the <scene name='2b5r/Blip/4'>hairpin loop between <font color='blue'>residues 46–53 in <font color='black'>BLIP (yellow). This rearrangement of the <font color='red'>loop is not observed in the <font color='pink'>unbound BLIP structure. This shows that the rearrangement of BLIP was caused by the TEM1 mutations, resulting in a new low energy state. <scene name='2b5r/Superpos/3'>Superposition of residues in wt and mutant complexes near the BLIP 46-53 loop. TEM1 <font color='cyan'>wt E104 and Y105 are colored cyan, while <font color='orange'>mutant E104Y and Y105N are colored orange. BLIP residues colored in <font color='blue'>blue and <font color='red'>red in the <font color='blue'>wt and <font color='red'>mutant complexes.

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About this Structure
2B5R is a Protein complex structure of sequences from Escherichia coli and Streptomyces clavuligerus. Full crystallographic information is available from OCA.